Remote ignition line



R. s. SHULMAN ETAL 3,296,963

REMOTE IGNITION LINE Filed June 19, 1964 REMOTE IGNITION LINE Robert SJShulman, deceased, ilate of Langhorne, Pa., by Jean Shulman Biberman, administratrix, Philadelphia,

. Pa.; and Thomas. Q. Ciccone Langhorne, Pa., assignors to the United States of America as represented by the Secretaryof the. Army Filed June 19,1964, Ser.:No..376,596 12 Claims. (Cl. 10227) The invention described herein may be manufactured and used by or for the Government for governmental 1 purposeszuwithout the payment to us of any royalty thereonm This invention relates to a device. for firing a gun at a saferdistance without danger of. shock and with an un- I usually light weight apparatus. An object is to provide 1 suchlian apparatuswhich is reliable, adapted to withstand I. allidegrees of natural temperatures andweighs substantially less than. 60 pounds for an entire apparatus capable of firing a gun at a distance of 75 feet.

Adanyard is open to the objection that its pull tends to move ;the gun off the target in a horizontal plane espeoially when not exactly in rear of the piece.

less rifle has. therbreech open to a flame issuing rearward whereforethis more modern weapon is not well adapted for: being fired exactly in rear. of it. Electric ignition Y becomes heavy .when consideration is given to a heavy d magneto or battery in addition to the wiring and its use is. not favored because electric ignition provides only heat andnot both heat and pressure and its connections become ditficult inextremes of weather. A field of com- 1: half mayalso be filled with stray magneticfields, radio impulses; etc; to endanger premature ignition.

A recoil- Specifically it has been found that a previously used 2 1 grains pera foot of PETN (pentaerythritol tetranitrate) toflone grain per foot and the protection of its entire length ini not onlygthe lead sheath previously used to absorb enj ergy by becomingyvaporized. but also enclosing the lead sheath in strong plastic fibers and in an elastic and abrasion resistant sheath of polyethylene.

M sonnel at eachend of the line additional protection for To further protect persayl ten feet; fromeach end has been provided with an I additionaltlayer of elastic or shock absorbing polyethylene, thena 1ayerof1woven fabric .of glass fibers, and

finallyl an outerlayer of polyethylene.

This PETN has a linear velocity. shock wave and some powden;

In wthe drawings:

FIG. 1 illustrates the preferred embodiment of this inf vention forfiring a gun. from a distance of about 75 feet awayfromuit.

FIG; 2 is an enlarged section on the line 22 of t FIG... 1.

At the rinitiating end of the present low energy detingqthe starting device 9 in. one hand and pulling ring 10 r with the other hand. This firing device 9 is not 1 broadly new anduincludes a firing pin 11 pulled with ring j lfl wagainst the spring 12 which is compressed by such pull. 1% When the pull has moved the connector 13 far enough for .it to be free of the guiding function per- UnitedStates Patent 3,296,968 Patented Jan. 10, 1967 formed by the end of device 9 adjacent the ring 10, the bevelled or inclined portion of this connector is released from the complementary end 14 of the firing pin with the assistance of the bevelled portion 14. On connector 13 being forced away from the firing pin 11 by these bevelled or inclined portions as soon as connector 13 is freed from the guiding cylindrical walls of the starting device 9, then the spring 12 drives the firing pin 11 forward with enough force for the blunt end 15 of pin 11 to strike primer 16 firing it and the PETN (pentaerythritol tetranitrate) in the reinforced cord 17. An aluminum body 18 around this cord 17 provides a slightly yieldable enclosure for'the detonating cord. As a convenience the reinforced cord is wound upon a spool 19 for substantially its entire length. A cotter pin 20 through the connector 13 or firing pin 14 prevents premature firing of this cord. A further safeguard against such premature firing before cord 17 has been unwound from the spool 19 includes a narrow plate 21 secured to the pin 20 and preventing pin 20' from being removed until all convolutions of cord 17 have been unwound from this plate, 21. A handle 23 for convenience in carrying spool 19 and its contents is sprung into holes 22 in an end of the spool.

The unwound cord 17 has its ends reinforced for about 10 feet or more from each end with the central part or main length 25 of the cord reinforced to a much less extent as will be shown hereinafter in connection with FIG. 2. The reinforced ends of larger diameter than longer central portion 25, are preferably provided with aluminum terminals 26 and 18. In each such terminal a booster of lead azide 28 is desirable for firing the core 27 and for enabling the fired core to penetrate an end of the terminal 26 and enable the primer in a gun to be fired. Best results accrue when terminal 26 substantially touches the primer in the gun to be fired, and when the primer 16 touches the adjacent end of the reinforced cord.

As shown in FIG. 2 where the cord reinforced ends are shown magnified, the central core 27 of PETN has been reduced from its formerly used strength in a blasting cord to only about a weight of one grain per foot of length, having a diameter of about .015 inch. Around this central core is a lead sheath 29 having a diameter of about .04 inch. When the core detonates the lead sheath is believed to be vaporized absorbing considerable heat of the detonation. Around the lead sheath is wound a 600 denier rayon layer 30 having a diameter of about .15 inch. Surrounding that is a layer of polyethylene 31 having a diameter of about .17 inch. This much of the cord applies to its entire length. Wherever used above and hereinafter the diameter given is an outside diameter for any layer.

The following portions of FIG. 2 apply to the reinforced or enlarged ends. Being an addition to an already formed cord, an air space of about .001 inch in thickness is-.provided to permit a sliding fit of the outer layers upon the previously described cord. This air space 32 acts as an attenuation means in that it helps reduce the shock waves created by the explosive. This is why the air space 32 is given a diameter of .172 inch. A polyethylene tube 33 having a diameter of .196 inch provides a good surface to slide over layer 31 and each is yieldable under tension due to internal pressure should the detonation for some reason be heavier than expected. The layer 34 having a diameter of about .220 inch is formed from a woven fabric of glass fibers and glass fibers are known to have a tensile strength exceeding many kinds of strongsteel. The outer layer 35 of polyethylene has a diameter of .244 inch and provides a satisfactory abrasion resistant coating in addition to possessing the other advantages mentioned for such a layer. Instead of having abrupt termination of the protective layers which extend from each end about feet, it has been found desirable to have them gradually taper off to the thickness of the mid-section and the ends coated with a moisture proof plastic to keep out fungi etc.

The chief advantage of this invention has been proven to be the protection of personnel at each end of the detonation cord. Another advantage i the small radius of bend to which the entire cord portions are able to withstand, as small as a bend around an eighth of an inch or less. The temperature range that this invention is able to withstand is from 40 to +160 F. The average weight for the entire cord is .75 pounds per foot. The strip 21 will be held in the position shown until the last convolution of cord Wound over it has been unwound before it may be raised into prolongation of the cotter pin 20 and only then is the pin 20 able to be withdrawn preparatory to pulling ring 10 for firing the cord.

What is claimed is:

1. In a low detonating cord having a core of pentaerythritol tetranitrate encased in a lead sheath, the combination therewith of the improvement for enhancing the safety and utility of such cord for firing a gun from a distance as well as reducing the weight of said cord, said improvement including said sheath enclosed in a layer of 600 denier rayon having a thickness of about 0.55 inch, a layer of polyethylene about .01 inch thick and said core within said lead sheath weighing only about 1 grain per foot and the lead sheath being about .04 inch in diameter, said cord being reinforced for about 10 feet from each end with a second layer of polyethylene about .196 inch in diameter, a layer of fiber glass woven fabric outside the foregoing about .22 inch in diameter, and an outer layer of polyethylene about .244 inch outside diameter.

2. A cord according to claim 1 in which cord is wound on a spool and provided with a pull device for firing said cord.

3. A combination according to claim 1 in which a primer for firing said cord is enclosed in an aluminum terminal.

4. A combination according to claim 1 in which an aluminum terminal is provided also at an end of said cord opposite its initiating end, and a lead azide booster material is enclosed in the terminal at said opposite end and such a booster is also enclosed in said primer at the initiating end of said cord.

5. A low energy detonating cord including throughout the length of said cord,

a lead sheath encasing said explosive core,

a sheath of strong plastic fibers encasing said lead sheath, and

a first sheath of elastic material encasing said plastic fibers, and at the handling end of said cord,

a second sheath of elastic material encasing said first sheath of elastic material, said first and second elastic sheaths being radially spaced from each other to provide an air space,

a sheath of fiber glass material encasing said second sheath of elastic material, and

a third sheath of elastic material encasing said sheath of fiber glass material.

6. A cord of the typedescribed in claim 5 wherein said explosive core is pentaerythritol tetranitrate.

7. A cord of the type described in claim 5 wherein said sheath of strong plastic fibers is made ofrayon.

8. A cord of the type described in claim 5 wherein said first, second and third sheaths of elastic material are abrasion resistant.

9. A cord of the type described in claim 5 wherein said first, second and third sheaths of elastic material are made of polyethylene.

10. A cord of the type described in claim 5 wherein said sheath of fiber glass material is woven.

11. A low energy detonating cord including:

an explosive core,

a lead sheath encasing said core,

a layer of rayon encasing said lead sheath,

a first layer of polyethylene encasing said layer of rayon, and

a second layer of polyethylene loosely encasing said first layer of polyethylene, said first and second layer of polyethylene sheaths being spaced from each other to provide an air space.

12. A cord of the type described in claim 11 including:

a layer of fiber glass encasing said second polyethylene layer, and

a third layer of polyethylene encasing said layer of fiber glass.

References Cited by the Examiner UNITED STATES PATENTS 2,715,365 8/1955 Godchaux et al. 10227 2,923,239 2/1960 Andrew et al. 10227 2,982,210 5/ 1961 Andrew et al. 10227 3,129,663 4/1964 Schnepfe 10227 BENJAMIN A. BORCHELT, Primary Examiner.

R. V. LOTTMANN, V. R. PENDEGRASS,

- 1 Assistant Examiners. 

1. IN A LOW DETONATING CORD HAVING A CORE OF PENTAERYTHRITOL TETRANITRATE ENCASED IN A LEAD SHEATH, THE COMBINATION THEREWITH OF THE IMPROVEMENT FOR ENHANCING THE SAFETY AND UTILITY OF SUCH CORD FOR FIRING A GUN FROM A DISTANCE AS WELL AS REDUCING THE WEIGHT OF SAID CORD, SAID IMPROVEMENT INCLUDING SAID SHEATH ENCLOSED IN A LAYER OF 600 DENIER RAYON HAVING A THICKNESS OF ABOUT 0.55 INCH, A LAYER OF POLYETHYLENE ABOUT .01 INCH THICK AND SAID CORE WITHIN SAID LEAD SHEATH WEIGHING ONLY ABOUT 1 GRAIN PER FOOT AND THE LEAD SHEATH BEING ABOUT .04 INCH IN DIAMETER, SAID CORE BEING REINFORCED FOR ABOUT 10 FEET FROM EACH END WITH A SECOND LAYER OF POLYTHYLENE ABOUT .196 INCH IN DIAMTER, A LAYER OF FIBER GLASS WOVEN FABIRC OUTSIDE THE FOREGOING ABOUT .22 INCH IN DIAMETER, AND AN OUTER LAYER OF POLYETHYLENE ABOUT .244 INCH OUTSIDE DIAMETER. 